129 lines
4.5 KiB
ArmAsm
129 lines
4.5 KiB
ArmAsm
/* $NetBSD: n_cabs.S,v 1.3 2000/07/14 04:50:58 matt Exp $ */
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/*
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* Copyright (c) 1985, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)cabs.s 8.1 (Berkeley) 6/4/93
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*/
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#include <machine/asm.h>
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.globl _C_LABEL(__libm_dsqrt_r5)
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/*
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* double precision complex absolute value
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* CABS by W. Kahan, 9/7/80.
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* Revised for reserved operands by E. LeBlanc, 8/18/82
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* argument for complex absolute value by reference, *4(ap)
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* argument for cabs and hypot (C fcns) by value, 4(ap)
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* output is in r0:r1 (error less than 0.86 ulps)
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*/
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/* entry for c functions cabs and hypot */
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ALTENTRY(cabs)
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ENTRY(hypot, 0x8040) # save r6, enable floating overflow
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movq 4(ap),r0 # r0:1 = x
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movq 12(ap),r2 # r2:3 = y
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jbr cabs2
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/* entry for Fortran use, call by: d = abs(z) */
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ENTRY(z_abs, 0x8040) # save r6, enable floating overflow
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movl 4(ap),r2 # indirect addressing is necessary here
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movq (r2)+,r0 # r0:1 = x
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movq (r2),r2 # r2:3 = y
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cabs2:
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bicw3 $0x7f,r0,r4 # r4 has signed biased exp of x
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cmpw $0x8000,r4
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jeql return # x is a reserved operand, so return it
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bicw3 $0x7f,r2,r5 # r5 has signed biased exp of y
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cmpw $0x8000,r5
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jneq cont /* y isn't a reserved operand */
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movq r2,r0 /* return y if it's reserved */
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ret
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cont:
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bsbb regs_set # r0:1 = dsqrt(x^2+y^2)/2^r6
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addw2 r6,r0 # unscaled cdabs in r0:1
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jvc return # unless it overflows
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subw2 $0x80,r0 # halve r0 to get meaningful overflow
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addd2 r0,r0 # overflow; r0 is half of true abs value
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return:
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ret
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ENTRY(__libm_cdabs_r6,0) # ENTRY POINT for cdsqrt
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# calculates a scaled (factor in r6)
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# complex absolute value
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movq (r4)+,r0 # r0:r1 = x via indirect addressing
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movq (r4),r2 # r2:r3 = y via indirect addressing
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bicw3 $0x7f,r0,r5 # r5 has signed biased exp of x
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cmpw $0x8000,r5
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jeql cdreserved # x is a reserved operand
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bicw3 $0x7f,r2,r5 # r5 has signed biased exp of y
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cmpw $0x8000,r5
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jneq regs_set /* y isn't a reserved operand either? */
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cdreserved:
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movl *4(ap),r4 # r4 -> (u,v), if x or y is reserved
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movq r0,(r4)+ # copy u and v as is and return
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movq r2,(r4) # (again addressing is indirect)
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ret
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regs_set:
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bicw2 $0x8000,r0 # r0:r1 = dabs(x)
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bicw2 $0x8000,r2 # r2:r3 = dabs(y)
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cmpw r0,r2
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jgeq ordered
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movq r0,r4
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movq r2,r0
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movq r4,r2 # force y's exp <= x's exp
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ordered:
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bicw3 $0x7f,r0,r6 # r6 = exponent(x) + bias(129)
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jeql retsb # if x = y = 0 then cdabs(x,y) = 0
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subw2 $0x4780,r6 # r6 = exponent(x) - 14
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subw2 r6,r0 # 2^14 <= scaled x < 2^15
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bitw $0xff80,r2
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jeql retsb # if y = 0 return dabs(x)
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subw2 r6,r2
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cmpw $0x3780,r2 # if scaled y < 2^-18
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jgtr retsb # return dabs(x)
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emodd r0,$0,r0,r4,r0 # r4 + r0:1 = scaled x^2
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emodd r2,$0,r2,r5,r2 # r5 + r2:3 = scaled y^2
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addd2 r2,r0
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addl2 r5,r4
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cvtld r4,r2
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addd2 r2,r0 # r0:1 = scaled x^2 + y^2
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jmp _C_LABEL(__libm_dsqrt_r5)+2
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# r0:1 = dsqrt(x^2+y^2)/2^r6
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retsb:
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rsb # error < 0.86 ulp
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